An outboard motor with a four-stroke engine generally has an oil pan for retaining lubricating oil. Since lubricating oil in the oil pan needs a periodic change, an oil drain hole is formed in the vicinity of the bottom of the oil pan to allow the lubricating oil to be discharged.
The oil pan is provided within an extension case located below an engine cover. The drain hole in the oil pan is generally blocked by a drain plug. A change of oil is done with the drain plug removed.
An outboard drain structure of this kind is disclosed, for example, in Japanese Patent No. 2624636 or in Japanese Patent Laid-Open Publication No. 2001-27110.
An outboard drain structure disclosed in Japanese Patent No. 2624636 is configured such that a recess is formed in a portion of a metal extension case made from an aluminum alloy, a drain plug faces onto the recess, and a drain cover of C-shaped cross section closes the recess. The drain cover is attached to the extension case with a set screw.
When draining an oil pan, first, the drain cover is removed from the recess. Then, the drain cover is oriented horizontally, and the proximal portion of the drain cover is hooked on a stopper provided in the recess. At that time, the drain cover opens upward to serve as a gutter. Next, the drain plug is removed from the oil pan to discharge oil outside via the gutter-like drain cover.
Since the drain structure is configured such that the drain cover is attached to the extension cover with the set screw, it is necessary to screw the drain cover using a tool, resulting in time-taking fastening and removing operations of the drain cover.
A drain structure disclosed in Japanese Patent Laid-Open Publication No. 2001-27110 is configured such that a drain plug of an oil pan is provided opposite to an opening formed in an engine cover.
The drain plug in this drain structure is exposed outside and is likely to show a stain of seawater.
It is thus desired to improve workability when changing oil without exposing a drain plug outside.